What "Mainline" Does and Doesn’t Mean

Growing up in evangelical churches, I often heard about some other branch of Christianity called “mainline,” but I never really knew what that meant. I just knew that “mainline” meant “bad” for some reason. It was a little like the word “communist.” I didn’t really know anything about communism, but I heard the word used a lot and knew that communists must be really evil people bent on destroying everything good and beautiful in the world.

But what does “mainline” actually mean? At the simplest level, “mainline” just means that you belong to one of the eight mainline denominations: American Baptist, Christian Church (Disciples of Christ), Episcopal Church, Evangelical Lutheran Church in America, Presbyterian Church (USA), Reformed Church in America, United Church of Christ, United Methodist Church. Sometimes people include other denominations, but these are the eight most common ones.

This isn’t terribly helpful, though. Now we’re left wondering what a makes a denomination “mainline.” So, to figure out more precisely what it means to be a mainline Protestant, we’ll have to figure out what “mainline” itself means. And that’s a trickier proposition because we have several mistaken ideas about the term.

1. Mainline does not mean “majority”

Several of these denominations are rather large. The United Methodist Church, the ELCA, and the PC(USA) are all among the ten largest denominations in America. But others are much smaller, and the RCA doesn’t even crack the top 25. Even as a group, it’s hard to see how these denominations could constitute the majority when they don’t include most of the baptist denominations or any of the pentecostal churches. So mainline churches clearly do not constitute a majority today. And, even in the early 20th century when the term “mainline” first began to be used, these eight denominations did not comprise the majority of America’s Protestants.

2. Mainline does not mean “mainstream”

These two terms often get confused. Generally speaking, though, “mainstream” refers to religion at its most popular level. It’s the normative religion in a given area. And mainstream religion in America is definitely not mainline Protestantism. Indeed, America is probably too diverse to have a mainstream religion. But if it did, it would certainly be evangelicalism (in the broad sense of the word). And, as we’ll see in a moment, mainline actually means almost the opposite of mainstream.

3. Mainline does not mean “liberal”

We actually need to be a little more careful with this one for two reasons. First, it would probably be more correct here to say that mainstream did not originally mean liberal, since that is in fact how many people use the term today. And second, the liberal/conservative tension was a part of where this term came from. It just wasn’t the dominant meaning behind the term. You’ll see what I mean in a moment.

So, if mainline does not refer to the “majority,” “mainstream,” or even the “liberal” aspects of American protestantism, where did the phrase come from?

“Mainline” refers to “establishment” Christianity

At least, that’s what it originally meant. The term “mainline Protestant” first began to be used in the early 20th century during the fundamentalist/modernist controversy. It appears that fundamentalists used it as a way of characterizing the debates. They presented themselves as the ones who were standing against a culture that was growing rapidly more corrupt. They were the “outsiders.” Their opponents, on the other hands, were the ones at the helm of the sinking ship. They held influential positions in government, education, media, and other aspects of society. They were the establishment.

Many have suggested that the term itself comes from an important commuter train line in Pennsylvania (thus the picture at the top of this post). Since the train line ran through a number of influential and wealthy towns, the line came to symbolize those who were in power in America. From there it would be a short step to using this as away of describing establishment Protestants. But I haven’t been able to verify that this really is where the term came from.

From this, you can see why I said earlier that “mainline” is actually the opposite of “mainstream.” The “fundamentalists” in the early 20th century would have seen themselves as part of mainstream protestantism, and they were probably right numerically speaking. And they used the term “mainline” to present their opponents as the cultural “elite.”

So, there’s a sense in which “mainline” originally just meant “not a fundamentalist.” Which is, of course, also why mainline came to be viewed as virtually synonymous with “liberal.”

And once the label came into popular use, it stuck. So regardless of whether these denominations really are the establishment today–and they’re probably not–we still refer to them as mainline.